Biocompatible Implants Research Articles

Material Homogenization of Human Femur Bone Material Using a New Weighted Approach

Abstract The design of efficient and safe biocompatible artificial implants for bone replacement and reconstructions requires a thorough understanding of natural bone material. A new homogenization approach is therefore used to predict effective material properties of the human femur bone. The bone structure is idealized as a functionally graded composite made of different quantities of a collagen protein matrix reinforced by hydroxyapatite mineral acting as the filler. Two distinct composite models were investigated, one where the mineral reinforcements were assumed to be randomly dispersed inclusions in a matrix of collagen, and a second model wherein the minerals were assumed to be unidirectional fibers. Predicted results for longitudinal and transverse elastic modulus from the models compare very well with range of values from published experimental data. It is also compared to those predicted using classical homogenization models. These material properties are then used to obtain the structural response of a bone plate section under transverse load.

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants.

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

A review of molybdenum disulfide-based 3D printed structures for biomedical applications

MoS2 is a substance, highly valued for its two-dimensional nanostructure and diverse physical and chemical properties. This review examines the advancements achieved in biomedical applications through the integration of molybdenum disulfide (MoS2), and the state-of-the-art area of 3D printing technology. It initially outlines MoS2 synthesis routes and techniques to tailor its properties. The review explores how MoS2 properties underpin its biological significance, thereby facilitating its therapeutic, tissue engineering, and biosensing applications. Emphasis is placed on the emerging area of 3D printing, assessing its potential when combined with MoS2 to produce customized materials for biomedical purposes. Strategies to create foam topologies and electrocatalytically active filaments in 3D-printed constructs are explained. The enhanced mechanical strength, conductivity, and therapeutic efficacy observed in 3D-printed MoS2 structures foreshadow new developments in healthcare, including the advent of biocompatible implants for regenerative medicine and tissue engineering. Further results show how innovations have been made in biosensing areas leveraging MoS2 3D printing. These insights, grounded in scientific research, medical practices, and technological advancements, position MoS2 as a flexible and innovative material with diverse applications across various biomedical sectors.

Customizable, biocompatible implants for dorsal nasal augmentation: An in vivo pilot study of eight polylactic acid scaffold designs.

Augmentation of the nasal dorsum often requires implantation of structural material. Existing methods include autologous, cadaveric or alloplastic materials and injectable hydrogels. Each of these options is associated with considerable limitations. There is an ongoing need for precise and versatile implants that produce long-lasting craniofacial augmentation. Four separate polylactic acid (PLA) dorsal nasal implant designs were 3D-printed. Two implants had internal PLA rebar of differing porosities and two were designed as "shells" of differing porosities. Shell designs were implanted without infill or with either minced or zested processed decellularized ovine cartilage infill to serve as a "biologic rebar", yielding eight total treatment groups. Scaffolds were implanted heterotopically on rat dorsa (N = 4 implants per rat) for explant after 3, 6, and 12 months followed by volumetric, histopathologic, and biomechanical analysis. Low porosity implants with either minced cartilage or PLA rebar infill had superior volume retention across all timepoints. Overall, histopathologic and immunohistochemical analysis showed a resolving inflammatory response with an M1/M2 ratio consistently favoring tissue regeneration over the study course. However, xenograft cartilage showed areas of degradation and pro-inflammatory infiltrate contributing to volume and contour loss over time. Biomechanical analysis revealed all constructs had equilibrium and instantaneous moduli higher than human septal cartilage controls. Biocompatible, degradable polymer implants can induce healthy neotissue ingrowth resulting in guided soft tissue augmentation and offer a simple, customizable and clinically-translatable alternative to existing craniofacial soft tissue augmentation materials. PLA-only implants may be superior to combination PLA and xenograft implants due to contour irregularities associated with cartilage degradation.

Effect of TiC nano-particle on microstructure evolution and tribological behaviour of Ti6Al4V composites fabricated via spark plasma sintering

This study explores the escalating significance of lightweight and biocompatible biomedical implants with a high strength-to-weight ratio, revolutionizing critical medical applications. Despite these merits, their widespread use is hampered by poor tribological performance. Investigating the impact of TiC nanoparticles, we synthesized Ti6Al4V (Ti64) powders with varying TiC content using spark plasma sintering. The resulting nanocomposites exhibited enhanced wear resistance attributed to heightened hardness and oxidation wear resistance. Notably, at 2.5 wt% TiC content, nanohardness reached 8.99 GPa, and specific wear rate significantly decreased to 4.2 × 10−9 mm3/N-m under constant loading (20 N, 1 Hz). This reveals substantial improvements compared to Ti64 monolithic alloys, emphasizing the potential for advancing implant materials.

Визначення білків гострої фази в крові щурів після імплантації поліпропіленових хірургічних сіток із покриттям на основі танталу та його похідних

At present, more than 30 types of polypropylene surgical meshes are available in the world, but the statistics regarding the secondary inflammatory process after implantation still remain disappointing. Since polypropylene surgical meshes do not decompose well in the body, they can stimulate the surrounding tissuesto develop an inflammatory process that causes adhesions. For the past 50 years, tantalum has been successfully used to produce biocompatible medical implants in surgery, orthopedics, and dentistry. Its excellent anti-inflammatory and antibacterial properties have been repeatedly noted, indicating the possibility of its use as a coating for mesh implants. In order to better predict the outcome after implantation of biomedical materials, it is important to determine the content of acute phase proteins, namely C-reactive protein, haptoglobin and ceruloplasmin. The aim of the study is to determine the content of acute phase proteins, namely C-reactive protein, haptoglobin and ceruloplasmin in the blood of rats after implantation of surgical meshes coated on the basis of tantalum, tantalum oxide and tantalum nitride. Materials and methods. The experimental group included 40 male rats of the WAG population. With the help of surgical intervention, a polypropylene surgical mesh measuring 15x15 mm was implanted between the abdominal wall and various sections of the colon. 28 days after surgery, the experimental animals were decapitated by cervical dislocation. Blood samples were used to determine the content of C-reactive protein, the content of haptoglobin and the content of ceruloplasmin. Results and discussion. The content of C-reactive protein in the blood of rats was statistically 260 % higher in the experimental group implanted with uncoated surgical mesh and 228.8 % higher in the experimental group implanted with polypropylene surgical mesh with tantalum nitride coating in compared with the results in the group of intact animals. Haptoglobin content was statistically 110.5 % higher and ceruloplasmin was statistically 52.6 % higher in the uncoated surgical mesh group compared to the results of the intact animal group. We obtained similar results in the experimental group, which was implanted with a polypropylene surgical mesh with a coating based on tantalum nitride. The content of haptoglobin was 130 % higher and the content of ceruloplasmin was 50.6 % higher statistically compared to the results of the group of intact animals. The C-reactive protein content was 113.3 % and 95.5 % higher, respectively, in the groups implanted with polypropylene surgical meshes with a coating based on tantalum and tantalum oxide compared to the results in the group of intact animals. The content of haptoglobin in the tantalum-based coating group was 83.8 % higher and the content of ceruloplasmin was 32.6 % higher compared to the results obtained in the group of intact animals. In the tantalum oxide- based group, the haptoglobin content was 60.1 % higher and the ceruloplasmin content was 29.3 % higher compared to the results obtained in the intact animal group. Conclusion. Based on the results of the study, it was established that polypropylene surgical meshes coated with tantalum and tantalum oxide significantly reduce the inflammatory reaction compared to uncoated meshes and meshes coated with tantalum nitride. This is supported by lower levels of key inflammatory markers, indicating improved biocompatibility and anti-inflammatory effects of tantalum and tantalum oxide coatings.

ГЕНЕРАЦІЯ АКТИВНИХ ФОРМ КИСНЮ ЛЕЙКОЦИТАМИ КРОВІ ЩУРІВ ПІСЛЯ ІМПЛАНТАЦІЇ ХІРУРГІЧНОЇ СІТКИ З ПОКРИТТЯМ НА ОСНОВІ ТАНТАЛУ

Introduction. Over the past 20 years, polypropylene has become the main material used in hernioplasty, and has proven itself as an excellent material for the restoration of the abdominal wall during hernia repair. Since polypropylene surgical meshes do not decompose well in the body, they can stimulate the development of an inflammatory process in the surrounding tissues, which subsequently causes adhesions. The development of a postoperative inflammatory process after implantation of polypropylene surgical meshes is observed in 30–40 % of patients. This affects the management of the postoperative period, increases the time of stay of patients in the hospital and their period of convalescence. These data force scientists to continue the search for the optimal surgical mesh, which would suit specialists not only from the side of the physical properties of the surgical mesh, but also from the side of its biocompatible and anti-inflammatory properties. Tantalum is successfully used to produce biocompatible medical implants in surgery, orthopedics and dentistry. In previous studies, we have repeatedly noted its excellent anti-inflammatory and antibacterial properties, indicating the possibility of its use as a coating for mesh implants. One of the typical responses to surgical intervention is the generation of reactive oxygen species by leukocyte neutrophils, which are signaling molecules that damage the endothelium of vessels and promote the migration of cells of the immune system to the center of inflammation. The aim of the study – to determine the generation of reactive oxygen species in leukocytes of rats of the control group and experimental rats with implantation of uncoated and tantalum-based surgical meshes. Materials and Methods. ROS generation was assessed in rat blood leukocytes using the dye 2,7-dichlo­ro­dihydrofluorescein diacetate (H2DCFDA) by flow cytometry 28 days after implantation of uncoated and tantalum-coated surgical meshes. Results and Discussion. Analyzing the obtained results, it was determined that the use of tantalum-based surgical meshes does not cause excessive generation of ROS by leukocytes, in contrast to the use of an implant without a coating. Implantation of uncoated surgical mesh caused excessive production of reactive oxygen species in blood leukocytes of rats, as evidenced by statistically significant differences in the mean fluorescence intensity of 2,7- dichlorodihydrofluorescein diacetate. Conclusions. The use of tantalum-based surgical meshes causes less generation of ROS in leukocytes compared to the use of uncoated surgical meshes, and does not provoke the development of adhesions and purulent-septic processes in the postoperative period, which is confirmed by a morphological study. This determines the possibility of their use in surgical practice to improve the durability and stability of use as biomedical implants and prevention of adhesion formation.

Enhancing biocompatibility and osseointegration of medical implants using ti based nanocomposite coatings

The surface of the replacement medical implant can be coated, which is one of the most basic and effective ways to develop and strengthen bones and increase their compatibility for the human body to solve problems with bone defects, such as the problem of releasing ions from some elements of the body Medical alloy implants are one of the major drawbacks in bone fracture surgery, and biocompatible implants are new ways to ensure that these implants work well. These implants play a major role in accelerating osseointegration processes, but at the same time they suffer from the problem of releasing niobium and zirconium ions, which may cause serious diseases to human health. To stop these toxic ions from releasing, a bioceramic nanolayer coating was put on the alloy's surface. This made it more biocompatible and stopped the toxic ions from escaping. Among several types of coatings, the best nanocomposite coating was selected. Three criteria and levels were used: voltage, time, and cocentartion. A Takeuchi statistical program was used to collect data on all the tests (thickness, adhesion, contact angle, and roughness) in order to find the best coated sample. The study then used atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) methods.

Analyzing the Surface Topography of Hafnium Nitride Coating on Titanium Screws: An In Vitro Analysis.

Background The use of surface coatings to enhance the properties lacking in titanium has attracted significant focus in recent times. Hafnium nitride (HfN) coatings could be explored as promising in the osteoinductive properties of titanium implants. HfN exhibits excellent mechanical attributes, such as hardness and wear resistance, and is often used as a coating on high-end equipment for protection. The findings from this research may carve a new path for the production and optimization of HfN coatings to enhance the longevity and augment properties of implant materials. Thus, the present study was orchestrated to elucidate the surface morphology of HfN coating, ultimately contributing to the advancement of dental implant biomaterials. Materials and methods A total of twenty samples of medical grade commercially pure titanium screws (2 mm diameter and 7 mm length) were procured from G. R. Bioure Surgical System Pvt. Ltd., Ravali, Uttar Pradesh, India, and ten samples were reacted with HfN (0.1 M) (Nano Research Elements, Kurukshetra, Haryana, India) in 100% ethanol and stirred continuously for about 48 hours. Then these screw samples were immersed in the prepared colloidal suspension and sintered for two hours at 400 degrees centigrade. The implant screws were affixed onto metal supports. The magnifications for photomicrographs at ×30, ×200, ×1,500, ×3,000, and ×5,000 were standardized. Elementary semi-quantitative analysis of both dental implants was conducted using energy-dispersive X-ray spectrometry (EDX) coupled with the field emission scanning electron microscope (FE-SEM) equipment (JEOL Ltd., Akishima, Tokyo, Japan). The software used for the analysis of the obtained images is SEM Center. Results The surface analysis using the scanning electron microscope (SEM) showed the coating of HfN over titanium screws. The difference in surface morphology of both the group of implant screws can be visualized under 40.0 and 10.0 mm working distance (WD) for both groups. The surface analysis using the EDX of uncoated titanium screws shows five elements in the spectrum: titanium (Ti), oxygen (O), aluminum (Al), carbon (C), and vanadium (V). The EDX of the HfN-coated screws has two additional metals dispersed in the spectrum, hafnium (Hf). The element characteristics are tabulated with their apparent concentration, k ratio, line type, weight percentage, standard label, and factory label for uncoated titanium screws and HfN-coated titanium screws. Conclusion The study evaluated HfN coating over medical grade commercially pure titanium. The surface topography of coated versus uncoated was visualized. The scanning electron microscope (SEM) images showed a homogenous coating over the titanium surfaces, and the EDX showed elemental dispersion of the coated implant. The study aims to provide a comprehensive understanding of the coating's surface morphology, which will aid in the development of more durable and biocompatible implants. This thereby provides a promising scope for further research of this novel metal coating for use in the biomedical sectors, specifically for dental implants.

Investigation of wettability and wear properties on 3D printed Polylactic acid/Molybdenum disulfide-Silicon carbide polymeric composite for sustainable biomedical applications

In the present work, investigations of the wettability, wear, and morphological study on 3D-printed polylactic acid (PLA)/molybdenum disulfide (MoS2)-silicon carbide (SiC) based composite have been performed. In the first stage, the PLA/MoS2-SiC composite was fabricated from the different types of filaments of 1.75 ± 0.10 mm size by taking MoS2-SiC as reinforcement at various extrusion temperatures (150°C–160°C) and screw rotational speed (3–7 r/min) of the extruder setup. The Taguchi L9 orthogonal array was used to design the experiments for 3D printing by varying the filament type, range of nozzle temperature (200°C–210°C), and infill density (40%–90%). The pin-on-disk (POD) setup was used for measuring specific wear rate (SWR) and showed the lowest value of 0.00141 g/N-m when composites were 3D printed by taking filaments manufactured at the parametric combination of 160°C extruder temperature and 7 r/min rotational speed, while 3D printed at 210°C nozzle temperature and 40% infill density. Contact angle (CA) values indicated that the reinforcement of MoS2 and SiC in PLA resulted in hydrophilic surface formation due to morphology and increased roughness (including mean roughness (Sa), mean root square of the Z data (Sq), and the highest peak (Sz)). The significantly increased surface free energy (SFE) of MoS2-SiC-reinforced PLA composite compared to pure PLA was reported which makes the prepared composite a promising candidate to be used for biocompatible implants with high wear resistance.

Biomimetic design of fibril-forming non-immunogenic collagen like proteins for tissue engineering

Collagen, a key component of extracellular matrix serves as a linchpin for maintaining structural integrity and functional resilience. Concerns over purity and immunogenicity of animal-derived collagens have spurred efforts to develop synthetic collagen-based biomaterials. Despite several collagen mimics, there remains limited exploration of non-immunogenic biomaterials with the capacity for effective self-assembly. To combat the lacuna, collagen like protein (CLP) variants were rationally designed and recombinantly expressed, incorporating human telopeptide sequences (CLP-N and CLP-NC) and bioactive binding sites (CLP-NB). Circular dichroism analyses of the variants confirmed the triple helical conformation, with variations in thermal stability and conformation attributed to the presence of telopeptides at one or both ends of CLP. The variants had propensity to form oligomers, setting the stage for fibrillogenesis. The CLP variants were biocompatible, hemocompatible and supported cell proliferation and migration, particularly CLP-NB with integrin-binding sites. Gene expression indicated a lack of significant upregulation of inflammatory markers, highlighting the non-immunogenic nature of these variants. Lyophilized CLP scaffolds maintained their triple-helical structure and offered favorable biomaterial characteristics. These results accentuate the potential of designed CLP variants in tissue engineering, regenerative medicine and industrial sectors, supporting the development of biocompatible scaffolds and implants for therapeutic and cosmetic purposes.

Exploring complications following cranioplasty after decompressive hemicraniectomy: A retrospective bicenter assessment of autologous, PMMA and CAD implants

Cranioplasty (CP) after decompressive hemicraniectomy (DHC) is a common neurosurgical procedure with a high complication rate. The best material for the repair of large cranial defects is unclear. The aim of this study was to evaluate different implant materials regarding surgery related complications after CP. Type of materials include the autologous bone flap (ABF), polymethylmethacrylate (PMMA), calcium phosphate reinforced with titanium mesh (CaP-Ti), polyetheretherketone (PEEK) and hydroxyapatite (HA). A retrospective, descriptive, observational bicenter study was performed, medical data of all patients who underwent CP after DHC between January 1st, 2016 and December 31st, 2022 were analyzed. Follow-up was until December 31st, 2023. 139 consecutive patients with a median age of 54 years who received either PMMA (56/139; 40.3%), PEEK (35/139; 25.2%), CaP-Ti (21/139; 15.1%), ABF (25/139; 18.0%) or HA (2/139; 1.4%) cranial implant after DHC were included in the study. Median time from DHC to CP was 117 days and median follow-up period was 43 months. Surgical site infection was the most frequent surgery-related complication (13.7%; 19/139). PEEK implants were mostly affected (28.6%; 10/35), followed by ABF (20%; 5/25), CaP-Ti implants (9.5%; 2/21) and PMMA implants (1.7%, 1/56). Explantation was necessary for 9 PEEK implants (25.7%; 9/35), 6 ABFs (24.0%; 6/25), 3 CaP-Ti implants (14.3%; 3/21) and 4 PMMA implants (7.1%; 4/56). Besides infection, a postoperative hematoma was the most common cause. Median surgical time was 106 min, neither longer surgical time nor use of anticoagulation were significantly related to higher infection rates (p = 0.547; p = 0.152 respectively). Ventriculoperitoneal shunt implantation prior to CP was noted in 33.8% (47/139) and not significantly associated with surgical related complications. Perioperative lumbar drainage, due to bulging brain, inserted in 38 patients (27.3%; 38/139) before surgery was protective when it comes to explantation of the implant (p = 0.035). Based on our results, CP is still related to a relatively high number of infections and further complications. Implant material seems to have a high effect on postoperative infections, since surgical time, anticoagulation therapy and hydrocephalus did not show a statistically significant effect on postoperative complications in this study. PEEK implants and ABFs seem to possess higher risk of postoperative infection. More biocompatible implants such as CaP-Ti might be beneficial. Further, prospective studies are necessary to answer this question.

Balancing beauty and science: a review of facial implant materials in craniofacial surgery.

Facial reconstruction and augmentation, integral in facial plastic surgery, address defects related to trauma, tumors infections, and congenital skeletal deficiencies. Aesthetic considerations, including age-related facial changes, involve volume loss and diminished projection, often associated with predictable changes in the facial skeleton. Autologous, allogeneic, and alloplastic implants are used to address these concerns. Autologous materials such as bone, cartilage, and fat, while longstanding options, have limitations, including unpredictability and resorption rates. Alloplastic materials, including metals, polymers, and ceramics, offer alternatives. Metals like titanium are biocompatible and used primarily in fracture fixation. Polymers, such as silicone and polyethylene, are widely used, with silicone presenting migration, bony resorption, and visibility issues. Polyethylene, particularly porous polyethylene (MedPor), was reported to have one of the lowest infection rates while it becomes incorporated into the host. Polyether-ether-ketone (PEEK) exhibits mechanical strength and compatibility with imaging modalities, with custom PEEK implants providing stable results. Acrylic materials, like poly-methylmethacrylate (PMMA), offer strength and is thus mostly used in the case of cranioplasty. Bioceramics, notably hydroxyapatite (HaP), offer osteoconductive and inductive properties, and HaP granules demonstrate stable volume retention in facial aesthetic augmentation. Combining HaP with other materials, such as PLA, may enhance mechanical stability. 3D bioprinting with HaP-based bioinks presents a promising avenue for customizable and biocompatible implants. In conclusion, various materials have been used for craniofacial augmentation, but none have definitively demonstrated superiority. Larger randomized controlled trials are essential to evaluate short- and long-term complications comprehensively, potentially revolutionizing facial balancing surgery.

Nondestructive evaluation of mechanical heart valve disc thickness degradation due to accelerated durability test using THz-TDS measurements

ABSTRACT Quality assurance and control during the mechanical heart valve components’ production process is paramount to mitigate most of the valve-related complications arising from valve replacement. Nondestructive evaluation of heart valve implants with complex profiles during production is challenging due to the biocompatibility requirements and clean room assembly conditions. This study first tested the UHMWPE disc of TTK Chitra mechanical heart valve models TC1 and TC2 using Terahertz imaging in reflection mode. The UHMWPE discs were raster scanned in X-Y directions to obtain a Terahertz-C scan to locate the macro defects due to wear out, and to distinguish between the true positive and true negative samples. The results were verified with digital microscope studies. Second, this study investigates a unique relationship between Terahertz imaging in reflection mode and heart valve disc degradation due to accelerated durability study. Third, the variation of disc surface roughness due to accelerated durability test was studied by Gaussian curve fitting analysis of fast Fourier transform of the Terahertz reflections. Finally, a comparison between the TC1 and TC2 heart valve model’s wear-out foot print was carried out using Terahertz C-scan. Our results imply that Terahertz time-domain spectroscopy has promising applications in NDE measurements of biocompatible implants.

A comprehensive review of Gum metal's potential as a biomedical material

The demand for low elastic modulus and biocompatible load-bearing implants has experienced a significant surge in recent times. Gum metal, a noteworthy category of β-Ti alloys, has gained substantial recognition in the biomedical field. This is primarily attributed to its remarkable blend of characteristics, encompassing non-toxic and biocompatible elements, a low elastic modulus, superelasticity, and high strength. Achieving these properties involves precise electronic criteria within their composition and substantial deformation, often through cold swaging. Recent years have seen innovative processing methods and alloy compositions to meet these requirements, expanding Gum metal's properties and applications. This review offers a thorough look at Gum metal, covering its discovery and highlighting its unique properties, with a particular focus on its relevance in the biomedical field. It critically analyzes the various phases of Gum metal and delves deeply into its deformation mechanism, unveiling its exceptional shape recovery capability even after significant deformation. Theoretical alloy design strategies for Gum metal are addressed, providing a glimpse into the ongoing efforts to optimize its performance for biomedical applications. The impact of oxygen on the Gum metal's properties is explored. The review also scrutinizes biocompatibility and corrosion behavior studies conducted on Gum metal, emphasizing its appropriateness for biomedical implants. Finally, various fabrication and processing routes for Gum metal are reviewed, offering insights into the techniques employed to harness its potential for practical applications.

3D PRINTING OF PCL TO FABRICATE POROUS SCAFFOLDS FOR BONE TISSUE ENGINEERING APPLICATIONS

The aim of this study is to print 3D polycaprolactone (PCL) scaffolds at high and low temperature (HT/LT) combined with salt leaching to induced porosity/larger pore size and improve material degradation without compromising cellular activity of printed scaffolds. PCL solutions with sodium chloride (NaCl) particles either directly printed in LT or were casted, dried, and printed in HT followed by washing in deionized water (DI) to leach out the salt. Micro-Computed tomography (Micro-CT) and scanning electron microscope (SEM) were performed for morphological analysis. The effect of the porosity on the mechanical properties and degradation was evaluated by a tensile test and etching with NaOH, respectively. To evaluate cellular responses, human bone marrow-derived mesenchymal stem/stromal cells (hBMSCs) were cultured on the scaffolds and their viability, attachment, morphology, proliferation, and osteogenic differentiation were assessed. Micro-CT and SEM analysis showed that porosity induced by the salt leaching increased with increasing the salt content in HT, however no change was observed in LT. Structure thickness reduced with elevating NaCl content. Mass loss of scaffolds dramatically increased with elevated porosity in HT. Dog bone-shaped specimens with induced porosity exhibited higher ductility and toughness but less strength and stiffness under the tension in HT whereas they showed decrease in all mechanical properties in LT. All scaffolds showed excellent cytocompatibility. Cells were able to attach on the surface of the scaffolds and grow up to 14 days. Microscopy images of the seeded scaffolds showed substantial increase in the formation of extracellular matrix (ECM) network and elongation of the cells. The study demonstrated the ability of combining 3D printing and particulate leaching together to fabricate porous PCL scaffolds. The scaffolds were successfully printed with various salt content without negatively affecting cell responses. Printing porous thermoplastic polymer could be of great importance for temporary biocompatible implants in bone tissue engineering applications.

Nano-topography and functionalization with the synthetic peptoid GN2-Npm9 as a strategy for antibacterial and biocompatible titanium implants

In recent years, antimicrobial peptides (AMPs) have attracted great interest in scientific research, especially for biomedical applications such as drug delivery and orthopedic applications. Since they are readily degradable in the physiological environment, scientific research has recently been trying to make AMPs more stable. Peptoids are synthetic N-substituted glycine oligomers that mimic the structure of peptides. They have a structure that does not allow proteolytic degradation, which makes them more stable while maintaining microbial activity. This structure also brings many advantages to the molecule, such as greater diversity and specificity, making it more suitable for biological applications. For the first time, a synthesized peptoid (GN2-Npm9) was used to functionalize a nanometric chemically pre-treated (CT) titanium surface for bone-contact implant applications. A preliminary characterization of the functionalized surfaces was performed using the contact angle measurements and zeta potential titration curves. These preliminary analyses confirmed the presence of the peptoid and its adsorption on CT. The functionalized surface had a hydrophilic behaviour (contact angle = 30°) but the hydrophobic tryptophan-like residues were also exposed. An electrostatic interaction between the lysine residue of GN2-Npm9 and the surface allowed a chemisorption mechanism. The biological characterization of the CT_GN2-Nmp9 surfaces demonstrated the ability to prevent surface colonization and biofilm formation by the pathogens Escherichia coli and Staphylococcus epidermidis thus showing a broad-range activity. The cytocompatibility was confirmed by human mesenchymal stem cells. Finally, a bacteria-cells co-culture model was applied to demonstrate the selective bioactivity of the CT_GN2-Nmp9 surface that was able to preserve colonizing cells adhered to the device surface from bacterial infection.

An NIR light-driven AgBiS2@ZIF-8 hybrid photocatalyst for rapid bacteria-killing.

Bacterial infection is the most common risk factor that causes the failure of implantation surgery. Therefore, the development of biocompatible implants with excellent antibacterial properties is of utmost importance. In this study, NIR light-driven AgBiS2@ZIF-8 hybrid photocatalysts for rapid bacteria-killing were prepared. AgBiS2@ZIF-8 exhibited excellent photocatalytic activity due to the rapid transfer of photoelectrons from AgBiS2 to ZIF-8, resulting in abundant reactive oxygen species (ROS) to kill bacteria. Meanwhile, AgBiS2@ZIF-8 exhibited a noteworthy photothermal effect, which could effectively convert NIR light into heat. Subsequently, the NIR light-driven antibacterial activity of AgBiS2@ZIF-8/Ti against S. aureus and E. coli was studied. The experimental results showed that AgBiS2@ZIF-8 displayed enhanced photodynamic therapy (PDT) and photothermal therapy (PTT) performance. Under irradiation with 808 nm NIR light for 10 min, AgBiS2@ZIF-8/Ti could effectively eliminate 98.55% of S. aureus in vitro, 99.34% of E. coli in vitro and 95% S. aureus in vivo. At the same time, AgBiS2@ZIF-8/Ti had good biocompatibility. Therefore, AgBiS2@ZIF-8/Ti showed potential as an antibacterial material, which provided a strategy to fight polymicrobial infections.

Biocompatible implants in orthopedics: bone tissue engineering

Introduction Technological advances in bone tissue engineering have improved orthopaedic implants and surgical techniques for bone reconstruction. This approach allows overcoming inconvenience of the paucity of autologous materials available and donor site morbidity.Aim To demonstrate advances of the past 30 years in the development of bioimplants providing alternatives to bone grafting in reconstructive orthopaedics.Methods Preparing the review, the scientific platforms such as PubMed, Scopus, ResearchGate, RSCI were used for information searching. Search words or word combinations were bioactive osteoinductive implants, bone grafting, bone reconstruction, hydroxyapatite, bone scaffolds.Results The main trends in tissue engineering in the field of orthopaedics are represented by construction of three-dimensional structure implants guiding cell migration, proliferation and differentiation as well as mechanical support. Association with bone morphogenetic proteins, growth factors enables proliferation and differentiation of cell types of the targeted bone tissue. A promising advancement should be biodegradability with a controllable degradation rate to compliment cell/tissue in-growth and maturation in limb reconstruction.Discussion This review presents and discusses the experimental and clinical application of biotolerant, bioinert and bioactive materials for reconstructive bone surgery. Future generations of biomaterials are designed to be osteoconductive and osteoinductive.Conclusion Properties of polycaprolactone (PCL) filled with hydroxyapatite (from 10 to 50 wt %) make this hybrid material with controllable absorption a promising strategy for reconstructive surgery in comparison to other materials.

Single‐ and Multiscale Laser Patterning of 3D Printed Biomedical Titanium Alloy: Toward an Enhanced Adhesion and Early Differentiation of Human Bone Marrow Stromal Cells

AbstractThis study explores the enhancement of biocompatible titanium‐based implants through surface functionalization for improved bone healing. Specifically, a near‐beta type Ti‐13Nb‐13Zr alloy is 3D printed using laser powder bed fusion and subsequently textured using nanosecond (ns) and picosecond (ps) direct laser interference patterning (DLIP) to create single‐scale and multi‐scale surface textures. On these textures, the cell behavior, morphology, metabolic activity and osteogenic differentiation potential of human bone marrow stromal cells are assessed using fluorescence microscopy and MTS assays. Moreover, tissue non‐specific alkaline phosphatase activity served as an early osteoblast production marker. Compared to untextured specimens, both types of textures exhibited higher metabolic activity and cell proliferation. Single‐scale ns‐DLIP textures encouraged cell extensions anchored in groove regions, while ps‐DLIP textures with hierarchical structures promoted cell extensions attaching to nanostructures on sidewalls. The groove width and nanotopographies in groove areas facilitated cell spreading. Surface topography, roughness, and surface chemistry (surface energy, wettability) influenced cell adhesion, proliferation, and differentiation. A comprehensive evaluation of DLIP‐generated surface textures, including their topography and chemical states, complements the factors affecting in vitro cell behavior. Overall, this research demonstrates the potential of surface‐functionalized 3Dprinted titanium for a novel generation of biocompatible implants.